As both a graduate student and post-doctoral fellow, Dr. Rosenberg has sought to improve our understanding of quality of life and treatment decisions in young women with breast cancer both because breast cancer is the most common cancer in young adults and because of the unique and substantial psychosocial issues young women face at diagnosis, during treatment, and in survivorship. As part of her dissertation work at the Harvard School of Public Health, Dr. Rosenberg examined the impact of treatment on sexual function and body image in young women with early-stage breast cancer. As a post-doctoral fellow, Dr. Rosenberg explored the decision among women with unilateral breast cancer to remove their healthy breast (known as contralateral prophylactic mastectomy or CPM), an extremely important issue given increasing rates of CPM in recent years in young women in particular, despite a lack of evidence for improvement in outcomes from this surgery. The career development and research plan proposed in this K01 application aims to build on this prior research and contribute to the literature, while at the same time preparing Dr. Rosenberg for a career as an independent investigator. Training in qualitative research methods, advanced quantitative methods, and decision science will enable Dr. Rosenberg to acquire new skills that will allow her to carry out each aim of the proposed research including conducting focus groups and key informant interviews with young breast cancer patients and survivors as well as physicians (Specific Aim 1); analyzing longitudinal cohort data collected as part of an ongoing prospective study of women diagnosed with breast cancer at age 40 and younger (Specific Aim 2); and conducting a comparative effectiveness study (Specific Aim 3) to evaluate the feasibility and effectiveness of a decision aid (vs. usual care) designed to improve breast cancer surgical decisions. The proposed research involves multiple stakeholders, including breast cancer patients, survivors, physicians from a number of disciplines, and advocates. The overarching aim of this research is to ensure that decisions about breast cancer surgery are fully informed, consistent with individual needs and values, and made in a setting where anxiety, concerns, and expectations are addressed. The training and career development plan detailed in this K01 application will allow the candidate to acquire the necessary skills to accomplish her short-term goals of learning and using new analytic methods, implementing a clinical intervention, and developing productive collaborations with advocacy groups. Dr. Rosenberg's past educational and research experiences have incorporated epidemiology, psychology, outcomes, and health services research. In supporting the proposed research, this award will allow Dr. Rosenberg to further integrate these areas, while expanding her research skill set, facilitating her transition to an independent investigator with the ability to lead epidemiological, qualitative, and intervention studies.